One type of tool belonging to the category defined above is previously known from the International patent application W089/07020.
According to the principle of the tool described in said patent application a pair of overlaying metal sheet members are joined together by lancing and forming a part of one member through an unblanked part of the other member. Thereafter a staking procedure is carried out on the lanced and formed part of the one member to an adjacent surface of the other member to secure the members together in overlaying relation.
Typically this type of tools or machines provide very high forces during the joining procedure, the opening, or gap, for introducing the workpieces is relatively narrow and the strokes carried out by the active machine elements are short and fast.
On one hand a narrow gap and short stroke could be chosen in order to give the tool a fast operation which of course gives a more efficient tool with more joints per unit time. On the other hand the same parameters are of course limiting the form and dimensions of the workpiece which could be operated on by the tool.
If, on the other hand a wider gap and longer stroke are chosen, without any compromise on the time for making a joint, the tool will require a more powerful drive unit. The implementation of this idea thus implies costs at two levels: investment costs for a larger high-power drive installation and higher energy costs for the operation of the tool.